UCSD finds genes possibly linked to autism

UC San Diego has inched closer to the root causes of autism, identifying genes that appear to go haywire before a child is born, preventing the brain from developing normally.

Neuroscientist Eric Courchesne says he and his collaborators found evidence that many genes basically misfire, producing an overabundance of brain cells in the pre-frontal cortex that affect a child’s social, language and communications skills.

The problem begins during the second and third trimester of pregnancy, the period in which most brain cells are created.

“Essentially, the wiring pattern for the brain goes wrong and you don’t get normal development,” said Courchesne, director of the Autism Center of Excellence at the UCSD School of Medicine.

The findings, published Thursday in PLoS Genetics, could provide insight about how to treat and prevent autism.

Scientists say that part of the brain of young people with autism is significantly larger than those whose brains develop normally. UCSD Autism Center of Excellence

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Scientists say that part of the brain of young people with autism is significantly larger than those whose brains develop normally.

The new paper builds on a line of research that Courchesne has been following for years. In 2003, he showed that there is a link between the overgrowth of the brain and autism. Then last November, Courchesne reported that the brain of male boys with autism had 67 percent more cortical cells than they should have. Such cells are created before birth and play a fundamental role in social, communication and cognitive development.

The latest study indentifies at least some of the genes that are responsible for the problem, and helps to explain how and when the dysfunction occurs.

“This is telling us a lot about the beginnings of autism,” said Courchesne, who arrived at his conclusions by examining brain tissue samples from younger and older people who are autistic. He said, “We were looking for the residual signature of genes whose activity was not normal.”

Courchesne looked for these genetic “echoes” in people aged 2-14 years old, and in people 17-57.

“We looked at older people because it is well known that autism changes with age,” Courchesne said.

The researchers found evidence that, at least in some cases, the brain was attempting to rewire and remodel itself.

“That doesn’t necessarily mean that the rewiring is being done adequately or accurately. It could be getting things further and further wrong,” said Courchesne. “But many autistic children get better. It could be that some of the remodeling is successful. I am very excited about this.”

He said the findings from the adults “are telling us that the brain development problem hasn’t stopped. It is on-going. There may be signals or genetic changes that are attempting to deal with the original problem.

“That would seem to offer a potential target for pharmaceuticals to improve the remodeling.”